Cloth straightening apparatus

ABSTRACT

A CLOTH STRAIGHTENER FOR KNITTED OR WOVEN CLOTH COMPRISES A SERIES OF FEED ROOLS AND CLOTH STRAIGHTENING ROOLS, AT LEAST SOME OF WHICH ARE DRIVEN AT DIFFERENT OR DIFFERENTIABLE LINEAR SURFACE VELOCITIES IN PREDETERMINED, ADJUSTABLE RATIOS. VARIOUS ZONES OF THE CLOTH, DEFINED BETWEEN SUCCESSIVE DRIVEN ROLLS, CAN THUS BE SUBJECTED TO DIFFERENT DEGREES OF TENSION. IN EACH ZONE, THE MINIMUN LEVEL OF TENSION IS APPLIED THAT IS FOUND NECESSARY TO THE OPTIMUM PERFORMANCE OF VARIOUS FEEDING, STRAIGHTENING, AND DETECTING OPERATIONS.

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CLOTH STRAIGHTENING APPARATUS Filed May 13, 1970 6 Sheets-Sheet 51212242212107 11701292008 IloZzeTZS'om 3 M (if/M46 flfior gys UnitedStates Patent 3,717,909 CLOTH STRAIGHTENING APPARATUS J. DouglasRobertson, Taunton, Mass., assignor to Mount Hope Machine Company,Incorporated, Taunton, Mass. Filed May 13, 1970, Ser. No. 36,848 Int.Cl. D06h 3/12 US. Cl. 26-514 20 Claims ABSTRACT OF THE DISCLOSUREBACKGROUND AND BRIEF DESCRIPTION OF THE INVENTION This invention has asits general object the reduction of deleterious stretching of light,delicate, or otherwise stretchable knitted or woven cloth in the processof straightening and aligning the cloth. It is another object to providean improved cloth straightening apparatus which feeds, straightens, anddetects the condition of the goods in separate zones in which the goodsare subjected only to the various minimum degrees of tension required toperform these operations most effectively. Further objects andadvantages of the invention will become apparent as the followingdescription proceeds.

The weft or transverse filler threads of woven goods frequently becomedistorted in finishing processes, and it is necessary to restore thethread formations to their original appearance at the time the cloth waswoven. This requires removal of bow to straighten the weft threads, andremoval of skew to align them at right angles to the warp orlongitudinal threads. Similarly, the courses of knit goods, which arethe rows of stitches extending across the cloth, sometimes become bowedand/ or skewed in finishing, and must be returned to their originalappearance as knitted, in the intended relation and at proper angles tothe wales or ribs of the knit goods.

It is conventional practice to correct distorted or misaligned threadsor courses by passing the cloth through a series of rolls which includeat least one curved roll, a straight roll which is mounted for tiltingmotion about an axis perpendicular to its rotational axis, and feed orpropelling rolls for maintaining tension in the goods as they pass overthe other rolls. The curved roll or rolls cause the length of travel ofthe central portion of the cloth to differ from the length of travel ofthe edges through the set of rolls. These rolls therefore serve tocorrect bow distortion, or curvature from edge to edge of the cloth, ofthe weft threads or courses of the woven or knitted cloth. The axle ofthe curved roll has a curvature parallel to an axial plane. The extentof the correction can be controlled by turning this plane of curvatureto different angular positions about the longitudinal axis of the roll.

Tilting of the straight roll creates a difference in the length oftravel of opposite edges of the goods, and proportionate differences inthe travel of the warp threads or wales located at various distancesacross the Width. This roll therefore serves to correct skewdistortions, in which the weft threads of courses are not perpendicularto the warp threads or wales, respectively.

Both the two types of straightening rolls require that the goods must beheld under some degree of longitudinal tension, so that any parts of thegoods whose length of travel is relatively reduced will not separatefrom the roll surfaces. Such a separation produces a hook-shaped, sinousdistortion of the weft threads or courses, which is not economicallyfeasible to remove and therefore results in a waste of cloth. Therequired degrees of tension to prevent this happening are not, however,the same for both types of straightening rolls.

The condition of the weft threads or courses is usually detected shortlyafter the goods emerge from the straightening rolls. Detection bymechanical means, which is the most satisfactory method, requires thatthe goods be held under a proper degree of longitudinal tension, andthis may have quite a differenent value than the optimum tension levelrequired in the straightening processes. Again, the feeding of the goodsto and from the straightening rolls may desirably take place under stillanother level of tension.

The net effect of these differing tension requirements for feeding,straightening, and detecting, has hitherto been that the entire span ofgoods through the roll array had to be subjected to the maximum tensionrequired for any one of the operations. This was necessary even thoughsuch a high level of tension might be undesirable or even injurious inthe other operations; and it caused the goods to be stretched to amaximum extent over the entire span through the apparatus. It should benoted that the amount of permanent stretch imparted to such goods perunit length depends not only on the applied tension, but also on theamount of time they are subjected to this tension, and hence on thelength of the span in which the tension is applied.

Briefly stated, according to a preferred embodiment of my invention,certain of the rolls in a cloth straightening array are driven withdifferent, or controllably difierentiable, linear surface velocities toestablish different tension levels in several zones extending betweenadjacent driven rolls. The differing minimum degrees of tensioncompatible with optimum performance can thus be established in theseveral zones where the feeding, bow correction, skew correction, anddetection processes are carried out. The ratios between the differenttension levels are established and maintained constant by proportioningthe speed of each roll to the measured speed of the next successive rollin the processing sequence. The speed ratios are controllable bymanually adjustable means, to obtain the optimum tension levels forprocessing various goods of greater or lesser delicacy andstretchability.

While the specification concludes with claims particularly pointing outthe subject matter which I regard as my invention, it is believed that aclearer understanding may be gained from the following detaileddescription of preferred embodiments thereof, referring to theaccompanying drawing, in which:

FIG. 1 is a sectional view in side elevation of a first form of clothstraightening apparatus made according to the invention, taken alongline 1-1 in 'FIG. 2, looking to the right in the direction of thearrows;

FIG. 2 is a plan view of the apparatus of FIG. 1;

FIG. 3 is a sectional view in side elevation, taken along line 3-3 inFIG. 2, looking to the left in the direction of the arrows;

FIG. 4 is a sectional view in side elevation, taken along line 4-4 inFIG. 2, looking to the right in the direction of the arrows; I

FIG. 5 is a fragmentary sectional view showing details of a driveconnection with a curved roll forming a part of the apparatus;

FIG. 6 is a diagram of an electrical speed control circuit forming apart of the apparatus; and

FIG. 7 is a schematic view in side elevation of a modified embodiment ofthe invention.

Referring first to FIGS. 1-4, a preferred embodiment of the improvedweft straightening apparatus includes a series of rolls comprising, inorder of the sequence of their engagement with the sheet of woven goods30; straight or right circular cylindrical rolls 1, 2 and 3;longitudinally curved bow-correcting rolls 4 and 5; a straight roll 6; astraight skew-correcting roll 7; straight rolls 8, 9 and 10; and afurther straight roll 11 which does not form a part of the clothstraightener assembly proper, but is used as a reference indicator ofthe velocity of the sheet as it leaves the apparatus.

The rolls are rotatably mounted in a frame comprising a pair of parallelrectangular plates 14 and 16 and a series of transverse tubular bars 18.Equipment mounted outboard of the plates 14 and 16 is enclosed byhousings 20 and 22, respectively, (FIG. 2) having removable cover plates24 and '26. The axles of the straight rolls 1, 2 3, 6, 8, 9 and 10 aremounted in pairs of conventional bearings 28 carried by the plates 14and 16.

An indefinite length of a sheet 30 of cloth is fed through the apparatusalong the sinuous path show in FIG. 1, in the direction shown by thearrows. The cloth is guided into correct alignment by suitable guidingapparatus, illustrated as a pair of precision guiders 32, of a typedescribed by my U.S. Pat. No. 2,417,447, issued Mar. 18, 1947. Each ofthese guiders comprises a pair of rolls 34 carried on a swinging arm 36,which is pivoted on an axis perpendicular to the plane of the goods 30.The rolls nip the cloth with a resilient grip. Turning the swinging arms36 tilts the rolls more or less relative to the length of the goods, andthereby serves to guide the goods to left or right. Tension springs 38bias eacharm 36 in a direction to engage peripherally-grooved wheels 40with the selvages of the goods. A balanced condition is achieved bydesigning the arms 36 with a suitable gravitational bias, opposed to thesprings 38, so that the wheels 40 continuously engage the selvages. Ifthe selvages move to left or right, the resulting change in the angle ofthe arms 36 and the rolls 34 guides the goods back to their originaltrack.

Each of the guiders 32 is carried on a frame 42, having grooved rollers44 which engage transverse rods 46 attached to the plates 14 and 16. Thespacing between the guiders may be adjusted to suit different clothwidths by operating a small motor 48 (FIGS. 2 and 3) mounted on theplate 14. This motor is arranged to drive a chain 49, which is trainedaround sprockets 50 and 52, and thence around idler sprockets (notshown) mounted inboard of the plate 16, and is connected to the guiderframes 42.

The goods 30 are led by the guiders 32 to the rolls 1, 2, and 3, some ofwhich may be provided with brakes for the purpose of applying backtension against forward passage of the goods. Whether such brakes aredesirable or not will depend upon the particular application of thecloth straightener and the types of goods to be handled. In theillustrated construction, disc brake shoes 54 and 56 (FIG. 1) arearranged to act on a radial end surface of each of the rolls 1 and 3,respectively. These brakes are of a conventional type, and no furtherdetailed description is believed necessary. The span of the goodsextending from the roll 1 to the curved roll 4 constitutes a firsttension zone, that is, a region in which a firstdifferentiably-controlled tension may be created.

The curved bow-correcting rolls 4 and 5 have axles 60 and 62,respectively, which are longitudinally curved parallel to an axialplane. The outer sleeves of these rolls are flexible, so that they mayrotate freely about the curved axles. Rolls of this nature areWell-known, and are described for example by my U.S. Pat. No. 2,393,191,issued Jan. 15, 1946.

The relative lengths of the paths of the central portions and selvagesof the goods, from the roll 3 through the curved rolls 4 and 5 to theroll 6, may be changed by turning the planes of curvature of the axles60 and 62 of the curved rolls about their longitudinal axes. As

shown in FIG. 1, the rolls 4 and 5 are aligned, with the planes ofcurvature of their axles lying in or parallel to a plane P. The rollsare so arranged that the length of the paths of the selvages E andcentral portion C of the goods are then equal, and no bow correctiontakes place. Means are provided for changing the positions of the planesof curvature of the axles 60 and 62 about their longitudinal axes, insuch a manner that they turn in unison through equal arcs, but inopposite angular direction. This has the effect of changing the relativepath lengths of the selvages E and central portion C; either may be madethe longer, depending on the sense of the angular displacements of theaxles. By these means, either a leading or a lagging bow of the weftthreads or courses can be straightened. A more detailed description ofthe bow-straightening action appears in U.S. Pat. No. 3,167,843, issuedFeb. 2, 1965 to William P. McCleary and myself.

The curved axles 60 and 62 are mounted for angular adjustment aboutlongitudinal axes x and y, respectively, which are offset from the endsof the axles as shown in FIG. 1. The axes x and y are determined by tWopairs of bearing assemblies 64, which are mounted on the plates 14 and16, and which rotatably support pairs of stub shafts 68 at either end ofeach roll 4 and 5. These shafts carry transverse arms 66, to which theprotruding ends of the curved axles 60 are pinned at 67 (FIG. 5). Asbest shown in FIGS. 2 and 4, a pair of sprockets 72 are secured on theshafts 68 projecting through the plate 16, and a drive chain 76 istrained around these sprockets in a manner to turn them in oppositeangular directions, together with the shafts 68, arms 66, and the curvedaxles 60 and 62. A stepping motor 77 and a gear reducer 78 drive asprocket 80 for positioning the curved rolls.

The surface sleeves of the curved rolls 4 and 5 are continuouslyrotated, independently of the angular positioning of the roll axles, byvariable-speed motors 82 and 84 mounted outboard of the plate 14 (FIGS.2 and 3). The curved rolls 4 and 5 thus serve not only for bowcorrecting, but also act as cloth-propelling or feed rolls. The motors82 and 84 drive tachometer generators 92, 93, and 94 through sprockets95, chains 96, and sprockets 98. The generators 93 and 94 are coaxial,and are driven in common by the motor 84. The same motors drivesprockets 85, chains 86, and sprockets 88 which are attached to stubshafts 90.

The shafts are received coaxially in the shafts 68, as shown in FIG. 5,to drive the outer rotatable sleeve of each curved roll 4 and 5. Eachshaft 68 has an axial bore 102 receiving bearings 104 which rotatablysupport the associated shaft 90, an extension shaft 106, and a universaljoint 108 which drivingly couples the shafts 90 and 106. The lattershaft is rotatably mounted on an axis which is parallel to the adjacentend of the roll axle 60, by means of bearings 110 set into the arm 66. Atoothed wheel 112 afiixed to the end of the shaft 106 drives a belt 114and a toothed wheel 116 which is attached to the end of the roll sleeve100. The belt drive is enclosed by a casing 118 mounted on the arm 66,which is afiixed to the shaft 68 by machine screws 120, only one ofwhich is shown. It will be understood from the foregoing that the motors82 and 84 may continuously drive the sleeves of the rolls 4 and 5independently of the angular positioning of the curved roll axles 60 and62 by means of the shafts 68 and arms 66. By proper control of therelative surface velocities of the rolls 4 and 5, a second tension zonecan be set up in the span between them, in which a level of tensiondifferent from that in other portions of the goods can be created.

Referring again to FIGS. 1 and 2, the goods 30 departing from the curvedrolls 4 and 5 pass over the straight roll 6, and thence through a largeangle of wrap around the straight skew-correcting roll 7 to the straightroll 8. The skew-correcting roll 7 is supported by a tilting frame 124which has L-shaped brackets 126 affixed at either end for supporting theaxle 128 of the roll. The frame 124 is pivotally supported at 130 on atongue 132, which is welded to an L-shaped transverse beam 134 forming apart of the frame of the apparatus. The assembly of the tilting frame124 and the roll 7 are supported for angular movement about the pivot130 by means of two pairs of rollers 136' mounted in arms 138 and 140afiixed to the outboard ends of the tilting frame. The arms extendthrough elongated horizontal slots 142 formed in the plates 14 and 16,and these slots guide and support the rollers 136.

The drive gear mounted outboard of the plates 14 and 16 is protectedfrom entry of lint and dust by attaching flexible spring strips 144(FIGS. 3 and 4) to the arms 138 and 140 to cover the slots 142. Thestrips are rolled up on spring-loaded drums 146 mounted at either end ofthe slots 142, so that the slots remain completely covered as the arms138 and 140 move back and forth.

As best shown in FIGS. 2 and 4, the assembly of the tilting frame 124and roll 7 is angularly positioned about the pivot 130 by a reversiblemotor 148, :which drives a sprocket 150 through a gear reducer 152. Achain 154 is trained about the sprocket 150 and an idler sprocket 156,and has its ends attached to the arm 140 by means which include atension-adjusting device 158.

Operation of the motor 148 in either angular direction drives the chain154 to re-position the tilting frame 124 and the roll 7 about the pivot130. This allows for an increase in the path length of either edge ofthe goods 30 from the roll 6 to the roll 8 about the roll 7, and aproportionately shorter path length for all other longitudinal elementsof the goods. A skew distortion of the weft threads or courses can becorrected by tilting the roll 7 to increase the, path length of the edgeat which the weft threads or courses are leading, and to adjust toproportionately shorter path lengths the longitudinal warp threads orwales spaced across the Width of the goods.

The roll 8 is shown in FIGS. 2 and 3 to have a drive sprocket 160 fixedat one end of its axle 162, for the purpose of driving this roll througha chain 164 and an additional variable-speed motor (not shown). Thisroll thus serves as a cloth-propelling or feed roll. Independent controlof the surface velocity of this roll makes it possible to set up a thirdtension zone in the span extending from the second curved roll 5, aboutthe rolls 6 and 7 to the roll 8. A different level of tension than thatexisting in other parts of the goods can be created in this span, tosuit optimally the paticular requirements of the skew-straighteningopertions of the roll 7.

A short span is established between the rolls 8 and 9 for the purpose ofdetecting distortions of the weft threads or courses as the goods departfrom the straightening rolls. A series of detectors 166 are provided, ofwhich any number may be used as appropriate to a particular application,although four are shown by way of illustration. The detectors aresupported by frames 167 and grooved rollers 168 on parallel transverserods 170, attached at their ends to the plates 14 and 16. The spacing ofthe detectors transversely of the goods may be adjusted to suitdiflt'erent cloth widths by operating a small motor 172 (FIGS. 2 and 3)mounted on the plate 14. This motor is arranged to drive a chain 174,which is trained around sprockets 180 and 182 (FIG. 4) mounted on theplate 16, and is connected to the detector frames 167.

The illustrated detectors 166 are made in accordance with US. Pat. No.3,350,933 issued to L. J. Smith on Nov. 7, 1967, which is assigned tothe assignee of this application. These detectors employ caster wheels184, which are pressed slightly into the plane of the cloth defined bythe rolls *8 and 9 to create local distortion patterns. The casterwheels are deflected angularly from a normal alignment with the lengthof the goods, if the thread formation of the weft threads or courses aredistorted from their normal and proper relationship to the longitudinalwarp threads or Wales of the goods. Such angular deflections aremeasured electrically and transmitted by cables 186 to a control circuit188 (FIG. 4).

The deflections of two or more caster wheels are simultaneously addedand substracted by the control circuit 188, to produce control signalsseparately indicating skew and bow distortions. A distortion of the weftthreads or courses which involves a combination of both types ofdistortions is divided into component skew and bow control signals. Anyresulting skew distortion signal is applied by leads 190 to operate thereversible motor 148 in a manner to tilt the skew-correcting roll 7 to aposition which will remove this distortion. Bow distortion signals areapplied by leads 192 to operate the reversible motor 77 in a manner torotate the axles of the curved rolls 4 and 5 to positions which willremove this distortion. The details of the illustrated detection andcontrol means are described more fully by the aforementioned U .S. Pat.No. 3,350,933, and as they form in themselves no part of the presentinvention, no further detailed description is believed necessary. Otherwell-known types of detection and control means may be usedalternatively to control the operation of the straightening rolls 4, 5,and 7.

The axle 194 of the cloth-propelling or feed roll '10 is driven by avariable-speed motor 196 (FIG. 3), through sprockets 198 and 200 and achain 202. This establishes a fourth tension zone extending between therolls 8 and 10, in which the tension level most suitable to thedetecting operation may be set up by appropriate control of the linearvelocity of the roll 10.

The skewing motion of skew correcting roll 7 tends to stretch one edgeof the web passing over it, and slacken the other edge. If the webreaches the detecting zone between rolls 8 and 9 in this condition, thedetectors do not func' tion properly and false signals may be developed.To avoid this the roll *8, and optionally also the roll 9, are wrappedwith a material with a high coefiicient of friction. This tends toprevent one selvage from slipping over the roll '8 with respect to theother selvage, thus maintaining a substantially constant tension acrossthe web in the detecting zone between the rolls 8 and 9. In someapplications, it may prove satisfactory to omit a separate drive for theaxle 162 of the roll 8, thus extending the third tension zone throughthe entire span from the curved roll 5 to the roll 10. The same tensionlevel would then prevail in the skew-straightening operation between therolls 5 and 8 as in the detecting operation between the rolls 8 and 10,but this may prove acceptable for some uses.

The motor 196 also drives two co-axial tachometer-generators 204 and 206(FIG. 3) through sprockets 208 and 210, and a chain 212. An additionaltachometer generator 214 (FIG. 1) is driven by a roll 11 spaced in thedownstream direction of movement of the goods 30, by means of sprockets216 and 218 and a chain 220. This provides a reference velocity signal.The roll 11 is not a part of the cloth straightener proper, and any rollprovided in a specific installation for other processing purposes willserve the purpose if it is located upstream or downstream and deliversor receives the cloth in a continuous, uninterrupted flow to or from thecloth straightener.

Referring now to FIG. 6, a circuit for controlling the relative speedsof the rolls 4, 5, and 10 is shown schematically. As the system isillustrated, it is assumed that the roll 8 is not to be drivenindependently, and that there are accordingly only three separatetension zones Within the cloth straightening apparatus: a first feedingzone extending through the braked rolls 1 and 3 to the first curved roll4; a second bow-straightening zone extending between the curved rolls 4and 5; and a third combination skew-straightening and detection zoneextending from the curved roll 5 to the driven roll 10. The tensionapplied to the goods before arrival at the roll 1, and after departurefrom the roll 10, is controlled by other apparatus suitable to aparticular application, and of a conventional nature.

The circuit includes speed control units 232, 234, and 236, which may beidentical commercially-available units suitable for controlling thespeeds of the DC. motors 196, 84, and 82, respectively, by supplyingthem with armature excitation voltages which are controlled bysilicon-controlled rectifiers in response to applied signal voltages.The output armature excitation voltages of the respective speed controlcircuits are subject to manual adjustment by the potentiometers 238,240, and 242.

The roll 11 drives the tachometer-generator 214 to provide a referencesignal, which represents the overall velocity of motion of the runninglength of goods. For this purpose, the roll 11 may equally well belocated ahead of the weft straightener, relative to the direction offeeding of the goods, instead of downstream as it is illustrated.

The reference signal generated by the tachometer 214 is supplied by alead 244 to the unit 232, whose output voltage is supplied by a lead 246to control the speed of the motor 196, and hence the linear surfacevelocity of the roll 10. This velocity may be adjusted by thepotentiometer 238 to be equal to, greater, or less than the linearvelocity of the roll 11. In a similar fashion, the roll drives atachometer-generator 204, whose output voltage is supplied by a lead 248to the control unit 234, which in turn supplies a voltage through thelead 250 for controlling the speed of the motor 84 and the roll 5,subject to variation by adjustment of the potentiometer 240. The roll 5in turn drives the tachometer-generator 94, whose signal voltage issupplied by a lead 252 to the unit 236, which supplies armatureexcitation voltage through a lead 254 for controlling the speed of themotor 82 and the roll 4, subject to variation by the potentiometer 242.

In the illustrated circuit, a closed loop system is used to obtain veryprecise speed control. The system accordingly includes the additionaltachometer-generators 206, 93, and 92, which are connected by the leads254, 256, and 258 to the input leads of the control units 232, 234, and236, respectively. The feedback signals thus supplied provide a moreprecise speed regulation, but the addi tional tachometers may be omittedin applications for which an open-loop system affords sufficientlyaccurate regulation.

It will be observed from this description that the linear surfacevelocities of the rolls 10, 5, and 4 may all be made equal to that ofthe reference roll 11, by appropriate adjustments of the potentiometers238, 240, and 242. In that case, a uniform degree of tension would beapplied to the goods in every zone through the weft straightener.However, in accordance with the principles of practice of the invention,the speeds of the rolls 10, 5, and 4 are diiferentiable; that is, thepotentiometers may be so adjusted that the speed of these rolls willassume a relationship that applies different degrees of tension to thegoods in each zone defined between these rolls. It will be understoodthat the tension in a given zone may be relatively reduced by runningthe roll at its origin somewhat faster than the roll at its terminus;and the tension in any zone may be relatively increased by reversingthis speed relation. The relative degree of tension in each succeedingzone can be controlled in an independent manner, and can be either moreor less than that applied to the goods in other zones or in the runsexternal to the cloth straightener.

The various degrees of tension applied in the different zones are soselected that the minimum tension consistent with the optimumperformance of each of the operations of feeding, bow correction, skewcorrection, and weft detection, is applied in each of the correspondingzones. In this way, the minimum tension is applied to the cloth for theminimum time, and the adverse eifect to delicate goods is reduced, whilethe various operations necessary to rectifying the weft threads orcourses are performed under the optimum tension levels. These differenttension levels are readily ascertainable in the operation of the clothstraightener on various types of woven or knitted goods, as will beappreciated by those skilled in the art.

A modified construction is schematically illustrated in FIG. 7, in whichthe straightening operations are carried out in the reverse order tothat of the apparatus in FIG. 1. That is, skew distortions are removedbefore how distortions. The operation of the skew-straighting rolls, ifplaced next adjacent to the detection zone, may disturb the detectorsmore than would bow-correcting rolls operating in the same location.This relatively greater disturbance is caused by large and rapidexcursions of the skewstraighting rolls, necessary because of theoften-sudden appearance of skew distortions.

The apparatus schematically illustrated in FIG. 7 includes the rollsshown in FIG. 1, all similarly numbered. In addition, straight rolls270, 274, and a curved roll 276 are provided for guiding the cloth 30 inthe direction indicated by the arrows, in a predetermined path throughthe apparatus with proper angle of wrap about the other rolls.

- Roll 270 might be equipped with a brake like that of rolls 1 or 3 inFIG, 1. A second straight skew-correcting roll 272, identical with theroll 7, is also provided to reduce the amount of angular displacementrequired of these rolls by doubling the cumulative skew-correctingeffort. The rolls 7 and 272 are supported by a pair of tilting frames124 and L-shaped brackets 126, both frames being pivotally supported onpins on a common axis, normal to the planes of travel of the cloth toand from these rolls. The positioning arm 140, previously described inconnection with FIGS. 2 and 4, is connected to both brackets 126, andthe motor 148 angularly positioned both rolls 7 and 272 jointly aboutthe axis of the pins 130. The consequent increase or decrease of thepath length of either edge of the cloth 30 is doubled with respect tothe change attained by a single skew correcting roll, for a given angleof tilt.

The cloth is passed by the roll 6 to the curved rolls 5 and 4, both ofwhich are angularly adjustable as described in connection with FIGS. 1-6for correcting bow distortions.

The curved roll 276, receiving the cloth from the rolls 3, 2, and 1,none of which are braked rolls in this embodiment, expands the cloth asit travels to the rolls 8 and 9, which form a short span for cooperationwith the detectors 184.

The rolls 4, 5, and 10 are driven by motors in the manner described inconnection with FIGS. 1-6. In addition, the curved roll 276 ispreferably driven by an additional motor (not shown) similar to themotors 82, 84, and 196 (see FIG. 6). This motor is coupled to anadditional tachometer similar to the tachometers 92, 94 and 204, and isconnected in a like manner to a speed-control unit similar to the units232, 234, or 236. The roll 276 is thus driven at a speed having aregulated and adjustable ratio to that of the roll 10, and takes itsplace in the speedcontrol chain to regulate the speed ratio of the roll5. Consequently, there are at least four separate tension zones definedwithin the apparatus: a first skew-straightening zone extending throughthe rolls 272 and 7 to the first curved roll 5; a secondbow-straightening zone extending between the curved rolls 5 and 4; athird clothpropelling zone extending from the curved roll 4 to thedriven roll 276; and a fourth detection zone extending between thedriven ralls 276 and 10, in which the detector wheels 184 operate. Thissystem isolates the disturbances of the skew-straightening zonecompletely from the detection zone.

It should be noted that the illustrated drive system comprising separatevariable-speed motors for each driven roll, may be replaced by otherwell-known variable-speed motive means capable of driving the variousrolls at controllably-differentiable linear surface velocities. Forexample, a common variable-speed motor, which in itself establishes thereference velocity of the cloth, may drive a series of variable-speedmechanical drives, such as the belt-and-cone type, one connected Witheach driven roll, and each arranged for individual speed control tomaintain predetermined ratios between the surface velocities of thevarious driven rolls.

What I claim is:

1 Apparatus for straightening and aligning the crosswise threadformations of a running length of distorted cloth to restore it tosubstantially its form when first made, while limiting the tensionapplied to that required for optimum performance of the straighteningoperation, said apparatus comprising, in combination:

an infeed roll engaging the cloth first and defining an infeed zoneextending therefrom toward the source of the cloth; at least onestraightening element engaging the cloth second and defining astraightening zone extending from said infeed roll to said straighteningelement;

adjusting means for said straightening element for selectively varyingthe path lengths of edge portions relative to central portions of saidcloth to correct bow distortions of the crosswise thread formationsthereof, and for selectively varying the path lengths of longitudinalthread formations spaced across said cloth to correct skew distortionsof said crosswise thread formations;

at least one cloth propelling element engaging the cloth third anddefining a zone for detection of the orientation of said crosswisethread formations, said detection zone extending from said straighteningelement to said propelling element; and

motive means constructed and arranged for driving said straighteningelement and said propelling element at different linear surfacevelocities having a predetermined continuously-maintained ratio, tocreate different levels of tension in the cloth in said infeed,straightening, and detection zones as required for optimum feeding,straightening, and weft detection.

2. Apparatus as recited in claim 1, together with speedcontrol meansconstructed and arranged for detecting the linear surface velocity ofone of said elements, and operatively connected with said motive meansfor driving the other of said elements at a different linear surfacevelocity in said predetermined ratio to the velocity of said oneelement.

3. Apparatus as recited in claim 1, together with speed control meansconstructed and arranged for detecting the speed of said cloth and thelinear surface velocity of one of said elements; said speed controlmeans being operatively connected with said motive means for drivingsaid one of said elements at a linear surface velocity different fromthe speed of the cloth and having a predetermined ratio thereto, and fordriving the other of said elements at a linear surface velocitydifferent from that of said one of said elements and having apredetermined ratio thereto.

4. Apparatus as recited in claim 1, in which said one straighteningelement comprises a curved roll.

5. Apparatus as recited in claim 4, together with a furtherstraightening element comprising a tiltable straight roll engaging thecloth in said straightening zone.

6. Apparatus as recited in claim 4, together with a furtherstraightening element comprising a tiltable straight roll engaging thecloth in said detection zone.

7. Apparatus as recited in claim 1, together with manually-adjustablespeed control means operatively connected with said motive means forcontrolling the ratio between said linear surface velocities in responseto the observed straightening action of the apparatus.

8. Apparatus as recited in claim 1, together with means engaging thecloth in said detection zone for detecting distortions of said crosswisethread formations and operatively connected for controlling saidadjusting means to straighten and align said crosswise threadformations.

9. Apparatus for straightening and aligning the crosswise threadformations of a running length of distorted cloth to restore it tosubstantially its form when first made, while limiting the tensionapplied to that required for 10 optimum performance of the straighteningoperation, said apparatus comprising, in combination:

an infeed roll engaging the cloth first and defining an infeed zoneextending therefrom toward the source of the cloth;

straightening elements including at least one straight roll and onecurved roll engaging the cloth second and defining a straightening zoneextending from said infeed roll to said straightening elements;

means for adjusting said curved roll to vary the path lengths of edgeportions relative to central portions of said cloth to correct =bowdistortions of the crosswise thread formations thereof, and means foradjustably tilting said straight roll to vary the relative path lengthsof longitudinal thread formations spaced across said cloth to correctskew distortions of said crosswise thread formations;

at least one cloth propelling element engaging the cloth third anddefining a zone for detection of the orientation of said crosswisethread] formations, said detection zone extending from saidstraightening elements to said propelling element; and

motive means constructed and arranged for driving at least one of saidstraightening elements and said propelling element at different linearsurface velocities having a predetermined continuously-maintained ratio,to create different levels of tension in the cloth in said infeed,straightening, and detection zones as required for optimum feeding,straightening, and weft detection.

10. Apparatus as recited in claim 9, said infeed roll, said curved roll,said straight roll, and said propelling element being arranged insequential order of engagement with the cloth.

11. Apparatus as recited in claim 9, said infeed roll, said straightroll, said curved roll, and said propelling element being arranged insequential order of engagement with the cloth.

12. Apparatus as recited in claim 9, said straightening elementsincluding two of said curved rolls.

13. Apparatus as recited in claim 9, said straightening elementsincluding two of said straight rolls.

14. Apparatus as recited in claim 9, said propelling element comprisinga roll, said motive means rotationally driving at least three of saidrolls at different linear surface velocities, together withspeed-control means constructed and arranged for detecting the linearsurface velocities of a plurality of said driven rolls other than thefirst in the sequence of said driven rolls; said speed-control meansbeing operatively connected with said motive means for controlling theratio between the surface velocities of each sequential pair of saiddriven rolls in response to the linear velocity of the second of thatpair.

15. Apparatus as recited in claim 14, together with speed-control meansincluding manual speed-adjusting means operatively connected with saidmotive means for independent adjustment of the ratio between the linearsurface velocities of each sequential pair of said driven rolls, inresponse to the observed straightening action of the apparatus.

16. Apparatus as recited in claim 9, together with means engaging thecloth in said detection zone for detecting distortions of said crosswisethread formations, and operatively connected for selectively controllingsaid adustmg means and said tilting means to straighten and align saidcrosswise thread formations.

17. Apparatus as recited in claim 9, said motive means being drivinglyconnected with at least said curved roll and said propelling element.

18 Apparatus as recited in claim 9, said rolls includmg, in sequentialorder of engagement with the cloth, two of said curved rolls, saidstraight roll, and said propelling element; said motive means beingdrivingly connected with at least said two curved rolls and saidpropelling element.

19. Apparatus as recited in claim 18, together with ad- 11 justablemeans acting to control the surface velocity of said infeed roll tocontrol independently the tension in the cloth in said infeed zone.

20. Apparatus as recited in claim 9, said propelling element comprisingat least two propelling rolls; said motive means being drivinglyconnected with said curved roll and said two propelling rolls; saiddetection zone extending between said propelling rolls and beingisolated thereby from said straightening elements.

References Cited UNITED STATES PATENTS 10 ton, Mass.

12 Robertson et a1. 2651.9

Sciola 2651.3

Robertson et a1 2651.4

Strandberg 2618.6 X Leitner et a1. 2651.5

OTHER REFERENCES The Easiest Way to Get Rid of Bows or SkeWs or Both,Mount Hope Machinery Co., 15 Fifth St., Taun- ROBERT R. MACKEY, PrimaryExaminer

